Directivity control of x-rays



l Bmw-m1 5R V x@ 2,63%554 f f Ii May 12, i953 J. s. BARTOW ET;

D-REQTIYITY CONTROL OF X-RAYS Filed oct. 5, 1949 s vsx1@@fa-:smet 1' faenas@ i Patentes-Mey iai-'95s earenr oericn' 2,638,554A DIRECTE/TTY COi'TROL 0F XJRAYS John B. Barton' and Jack A. 1a'rto-v, Blue Bell,

and Grey D, lJacLaugb-lin, Jr., Pcrkionxenville, P a., assignors to. liar-tow Beacons Inc., Blue Bell,

Pa., a corporation of Pennsylvania Application-October, 199,Seriii1N-o. 119,734

8 Claims.

This invent-ion relates to directivi'ty control of X-rays, and while it is intended for application wherever useful, i--t is particularly applicable to X-ray.. treatment of the human body. The term Ii-rays," as used herein and in the appended claims, is intended to include all rays which may be produced in the practice of the invention and which have the properties of socalled X-.rays For example, certain of the gamma rays are in this category.

It is a matter of common ic'riowledge that X-rays are 4being used to an ever-increasing extent in the treatment of ailments of the human bodyfparticzxlarly in the treatment'of malignant growth-s vsuch as cancer. Hereto'fore, how- \e'ver, treatment by means of X-rays has been limited by' the inherent deleterious effect of such rays upon healthy bodily tissues. X-'ray treatment of cancer, for example, usually requires impingeinent of X-rays on a diseased spot er `ccnl area inside the body, and this necessitates projection of such X-rays through the skin and tis- -sues which are thus subjected to the destructive effects of such rays. While the ss'zin and healthy tissues can withstand moderate loses" of X-rays, they 'cannot withstand any prolonged concentration of such rays Without harmful eieots.

It has long been realized that if X-rays could be focused, it would be 'possible to concentrate a large number of such rays upon-an internal spot or local' area of .the human body without subjecting the skin and .tissues to harmful concentration of the rays. However, at present X-fays 'cannot be 'Dent or deflected, and this fact has heretofore precluded a successi-ul solution of the problem.

The practice in the past has been to project a narrow beam of X-rays into the body and onto the affected spot o1' area to be treated, This has necessitated movement of the beam angularly, 'while keeping it directed agaiirt the affected spot or area, in order to -avoid lprolonged subjection of .any one skin area to the concentrated rays. At best, this practice is far from satis factory. It involvesservious risk of X-ray burns.

and urtherniore itis extremely limited in effectiveness because of the limited number of X-rays that can be projected in a narrow beam.

, The principal object of the present invention is to provide a method and apparatus by which X-rays can .be effectively focused to produce concentration o such rays ata focal point or area. Another object of the invention is to provide a novel X-ray lens for the stated purpose.

A further object .of the invention is to provide I n l l novel constructions ci 'such lens and novel Irfl'ethod of making the same.

' A further object of the invention is to provide novel X-'ray producing devices embodying the lens.

'Other objects of the invention will be apparent -from the following detail'edclescription with reference to the accompanying drawing, wherein:

Fig. 1 is Ia diagrammatic illustration showing the use of the .novel lens in conjunction with an Ordinary X-ray tube;

Fig. 2 is a perspective view of the X-ray lens member as utilized in theapparatus of Fig. l;

Fig. 3 is a greatly enlarged fragmentary sectional View illustrating the broad principle of the invention;

Fig. 4 is an elevational vie-W of a siin-plied embodiment;

Fig. 5 is a perspective view of a segment of a preferred form of the lens;

6 is a fragmentary perspective View of the segment taken freni-the opposite side;`

Fig. '7 is a perspective View lof a frame for supporting the lens segments;

Fig. 8 is a perspective -view of the complete-lens assembly;

Fig, 9 is a sectional View taken on line S-9 of'Fig. 8;

Fig. l0 is a. .sectional view taken on line Ill-I0 of Fig. 8;

`Fig. 1l is a detail sectional view taken .on line H- H of Fig.' 8;

Fig, 12 is asectionel view similar to Fig. .l1 but showing a modification;

Fig. 13 is an illustration of a mul'tiplearrengement of lenses;

Figs. 14 to2- 0' are illustrations of various X-ray prcsscing Vdevices embodying the invention;

Fig. 21 is a plan vicwof en apparatus embodying the X-ray lens in conjunction witha movable X-ray' tube;

Fig. 22 is a Asectional View taken 'along line grammatically at l0 a--c'onventional XL1-ay tube which constitutes a source of X-rays represented at Il. As is well known, theX-:ass H are given un, nl i.

y.emplery ine-theo escorial oi by the anodic targetl i2 as the latter is struck by electrons, represented at 3, from the cathode- !4. For the purpose o this description, it may be assorti-ed that the tuloe Il) is adapted to produce hard-X-rays, as well understood in the art.

Below the tube f is-a secondary ter l5 which may ce in the `form of a, thin plating, e. g. gold or lead, on a 'plate or disk l5, which isof such character that it -constitutesa filter and absorbs soit X-rays while perntitling hard X-rays to pass through it. fIli'splo-te -or disk may be 'composed of any material, Wg. aluminun, which has the desired filtering property. Y

Belowthe disk 1 6 and adjacent thereto fis the X-ray lens i7 which serves to produce u focusing effect, i. e. the concentration of 'lzard ifi-rays at a focal point or area; rlliis ,len-s member .il Lis a relatively thick ho'dy composed of lead or 'my other Asuitable material which is non-tran :1ssive to -hard 'Iii-rays, said body being .prov'ded with Vmultitudinous rectilinear ysive elements which are conifergenrtoward a' ,point -These rays are rel sented -in i at I3 and they are shown meeting at po-int The manner in which these rays are selectin-'ely transirlit'te'cl will "Le .described .presently with the eid i of Figya.

`W i-ile the lens .men-iber- .lTI can A: ldesired, it is shown in the `form of .truncated cone, .as be Aclem-lj: seen in Fig. 2. The"cransiniss'ive elements o the lensmemiier may -be open holes dei-ning air vinessages, since air is tiansrnissive to '2-r he lledpartly or, holly witlrnmterial, such as elastic, which is .lss'ive .to "iE-rays. EX- of eoustructin .the lens member will be descri'. ed later. In il g. 2, the transmissive-elernents are shown arranged spiral jout these elements may -be arranged .in-any other manner. -For e .shaped .as

i ini" Considering ingreater Adetail the .operation of the arrangement, shown in Fig. 1, wiilhe apparent to thoseslzilled in the art that practicallyevcry point on the' ugpcr sui acc ofthe secondary emitter 45 will he str cx by :an X-ray Tromtube TU', and at each point-secondary X.-

rays will oe radiated in all directions 'sc-nie of which are hard and others of which are soft. lhisrisdepictecl .Fifn vwherein a single X-ray Zi from tube i8 is s wn si icing the upger surface of the second-1y emitter V5 at 'peint 22 which .is e'. ned -n-'ith a trasmissive element 2.3

of lens rnser ll, Rediating from point 22 in all directions are soft :XI-rays reprf-:sented by the shorter arrows24 and hard X-'ra-ys represented by the .longer :arrows 25. The do.:nr\-'ardly 'directed' -soft X-raysl vare friser-ned by the filter disl'` I8 which Vthe downwar sf-directed herd X- hard X-rays are selectively trensmited imm-sur-- a'c'e'potnts of 'the'secon:la-ry emitter I5 to a coro.-

X-ray emitf's, or the holes may 'rays are not. The-latter, bang of hierher energy mon focal point or area.

In practice lthe transmssive elements Awill be very small in 4crosssection. e.. g. of the 'order of .0L-ll" to 0.25" 'in diameter, the exact size depending upon thesize ofltlie focus desired in any instence. It will be apparent therefore that a very large number of such elements may be provided `in the lens 'member YFl which may be 'of 'the oriierio three to twenty inches in diameter.

:ents are to oe in the-.form of open holes, the iyiiesmey Vbecomo a materiel 'which canibe removed after the .lons ,member .is molded. For example, .the wires could be -formed of Sonie metal which could be removed by chemical action, .after molding of the member Il, -v-.fithout affecting the latter incm'ber. This could be accomplished liy forming the wires of a :material which would react vto Sonie acid to n'liich .the lead member' l': would not react. 'If the wires :are not to be removed from the holes, the .Wiresanay be formed o' a plastic material which .is .transmissive to X-rays, in which case it would only .he necessary to eutthe wires .at the. surface of .the ineinhc-r l' after the latter is molded.

Referring now to Fig. there is .shown-therein another embodiment of .the invention in -which it is unneeessary'to iisean 221 mary :source of X-raysin this instance thereis .provided o plete or disk 2'5 which in itself is source of X-rays. The disk may be .formed-of some material which isnaturolly radioactive, or it may be fort eed of .ainatcrial which, f' "hile not naturally radioactive, can he iliade radioactive. In either cese the' disk 25 will provide a multiplicity o point sources, each of which will radiate X-rays/ ln all directions.

Scio-w the disk .2G :and adjacent thereto 'is a lter plate or disk `'Z2' which 'corresponds -t'o the 'filter disl: IG of the iiodiment.

str-desc "e' .c This disl; .servestoahsorb or Til-ter lout the soft r-cysradiated by the-Clisi; 2S.

'Below and adjacent to the disk-2 is a lens memberlsiznilcr to .the `lons mrnber Il of the L-clescrihed e -badhuis-nt. lens member' ne-ly transmits certain ci the hard 2li-rays from disk toward :i focus point, these rays LU boing re` resented' at 25 ond the focus point beingsho :n atl.

ng descrip- `=-on that the ini'zn s e; 'the -provision o f any sutnhiesonrce of X1' irs, .and .the

selectiil'etransniisri 11 yof of-"ten of .the radiated X-rays arong rect neari .hs converging' toward a 'focal point or aree. As shown by the .a .vovo-desc 'ibed embodiments, the source which supplies the radiated rays for. selective .tra-nsssicn may be a secondary source or it may be a primary source. As hereinbefore mentioned, the present invention is .particularly Aapplicabletoflic X.- :ay tirez.

ment of internal A,parts ofthe human hotly, and

y tube as a .pri-

5 tration of the X-rays. Due to the 4ira-ct that the transmitted X-rays are discretel'yspaced from one another where they penetrate the skin and tissues, there is' no concentration except at the focal point or area. In other words, the rays are spread over a substantial area of the skin and therefore they do not produce any harmful-effect upon the skin or tissues.

Of course, even with the spacing of the X-rays at the skin and tissues it wouldbe unwise to subject any particularpointor spot on the slain to prolonged exposure to an X-ray. "Iherefore, in any prolonged treatment of a particular. internal spotor area it lis advisable to move the projected X-rays while keeping them focused 'onthe same spot or area, in order that difiere-nt points or spots on the skin will be exposed to the X-rays. This is readily accomplished by moving .the X-ray proiectlng :apparatus relative to the body being treated. Consider, for example, movement of the device of Fig. 4. The movement may be translatory, in which case the device is moved singularly about the vfocal point as a center. Or the Inovernent may be one of rotation, in which case Athe device is rotated about the axis of symmetry of the lens. By suitable arrangement of the transmissive elements ofthe lens, the rotational move- :nent can be made to give coverage of practically all points of a skinarea so that they will all share the X-ray impingement. The spiral larrangementas shown in Fig. 2 will achieve this end, as will' also the preferred lens construction no'v to be described. l

Figs. 8 to 12 illustrate a preferred' construction of the lens member and a preferred method of making tl e same. According to this method, the lens member is made up of a plurality of segmenti; of lead or other suitable materlaL-such as shown at l linl'ig.A 5,7-the sections collectively forming the complete lens member. to Fig. 5 the section shown is arcuate lengthwise and is tapered bothvridthwise and depthwisc, so that it is actually-a section of 'a sphere. Along each vface of the segment there are pro- 'vided s inall grooves 3.2., all of which converge toward o. com-mon focal point which 'coincides with the center of a sphere Aof which the segment is a section. A plurality of Such segments-are placed side by sdc, as shown in Fig. 8, to form the cornplate lens member 33, and they are held in asseinbled. relation in any suitable manner, as by means of a. fra-ine 34 which may be utilized as an assembling frame'. As may be seen in Fig. 8 the grooves of adjacent segments are offset from one another or in staggered relation. It will be noted also that the end segments 3 la and 3Ib are provided with grooves only along their inner races. The corner edgesof the assembled lens member are convergent toward a point 35, and the passages 'formed by the grooves are also con'- vergent toward thatpoint. Thus the assembled lens member is actually a segment oi a sphere whose center is. the point S5, and all of the X-rjay transmissive passages of the lens members are convergent twoard that point. Tais is ymore clearly apparent from the sectional illustration.

Reiferrin'g .A

recesses 38"-and 3'! at-.its yvends. as shoivn in Fig. 5

.saidrecesscs heir-1g conformed to the -sides of the inittcd through any minute space that may exist between the assembled segments, cach segment is provided with a rib 38 on one face and a recess 39 ontheother face, as shown in Fig. 5.' The ribs and recesses of .the segments intert with one another, as .may be seen in Fig. 9. Each ribis provided with slots 40 so as not to interfere with the transmission of X-ray-s through the convergent passages. This arrangement preients the existence of any rectilinear path through which X-rays might pass, except the convergent Apassages of the lens member.

l It is inevitable that some of the Xrays enteringthe passages of the lens member will strike the internal surfaces of the passages and will cause the production o f secondary X-rays. In order to-eiect absorption of 'such secondary X- rays and to prevent them from passing out'of the lens member, the surfaces of the passage-forming grooves are provided with ridges as shown-at 4l in Fig. l1,` and the face portions of each seg-.

ment which cooperate with the grooves of ad-A jacent scgments are also provided with ridges as shown at t2 and i3 in Figs. 5 and 6. These ridges may be provided by coining or in any other suitable inanner. These ridges cause any-secondary Xerays produced within the lens member to be trapped and absorbed.

Preferably, the ridges are shaped as shown at 45 in Fig. l2 to provide shoulders of progressively 'greater spacing. 'X-rays such as represented at IE5 which enter the passage at va substantial angle will strike one of the shoulders, and the .secondary rays produced thereby will radiate back toward the entrance'or will be absorbed. .Other X-rays, such as represented at 1.18, which do not strike the shoulders will pass through the lens.

As mentioned above, the segmental construction of the lens member enables multiple assemblage. Since the lens member is 'actually a.

segment of a sphere, a plurality of such mem- ,bers may be assembled and they will all Vhave a. common focus point. Fig. 13 shows' tivo assembled lens members. 4l and i8 which 'are simply placed side by side. This multiple assemblage may loe-extended to cover any section of a sphere.

Figs. lll to 2O show various X-ray producing Vdevices embodying the invention, and it will be Aapparent from these illustrations that the inven- 1 tion is capable of many embodiments of Whi.: those illustrated'are merely examples.

in Fig. 14 there is shown an Xfray tube comprising a glass envelope portion 43. a cathode assembly 5o si-nroorted thereby said adapted to produce an elec :on stream' 5l, a metal envelope portion 52, r lons 53 of the character above described, lln X-ray emitter 54, which may i I' www 7' the lens bemoei-.5 3 .will feinitvmi'iy l4raysftehieh are convergent toward '2; `ocal point crere.

111i 'some nstnces itms abe'tiesir'ztivle to utilize a .narrow electron .beam :and to sean .am Xen? producing surface.V Fig. 15 shows a tube' 5S having .a consentionol Y13e-em-forrning nrrengement 'er gun as regir salted generally at t9, :and also presided with 'deecting ple-tes 51. At the tei-get end of the tube there is provided an X-ray iens 62 :and anXJrny producing surface 163, ii'hidh may be scanned .'oy the 'electron beam.

An application of this type or tube is shmvn' in Fig. l- *wherein ijlie X- ogy tube is yo'c-,signevted EL In. the arrwgement shown, the 'electron begun 'is deflected :11,1 a 4scanning inotionrend .it is also turned on end -oif "by meen-s of a' control grid 85. A monosoope '55 is utilized lfor the iatter purposes. The electron -lbearnsoflooth tubes are given emisor-cnous lscanning motions by a. common sca-mung vgenerator '67 vili-ici: generates the scanning voltages that are applied to the de# liecting plates of the tubes. The target. vplatte G8 of the monoscope has .fa pott'ernthereon corsresponding to the pattern of t'ne ventrance ieee of the X-ray ions 63. The signal produced by the incncecope is tossed throng-li n video cmolier 'I8 and is applied to the grid 850i the X41-ay tube so as to key the electron lteatri of that tube- Bytliis arrangement the electron bea-m is tuifned on only when lit will strike the porti-ons of the X-i-ay-emitter H 'ad-jacent tl'ie passages -of lens 83. l

In some instances it may be .advantageous .to use a negatively charged grid to effoetconoentration -of the electron -str'ee-in at tle portions of the X-ray emitter ,adjacent the lens. This is i1- lustrad Figs. 17 end 18 wherein a negetivelfvY of a material, such -as lead, which is substantiely .non-transinssive to X-rays.

.A carriage 'H3G is arranged for .movement on the tracks Sii and .55, the carriage being provided with rollers -gll and 62 et opposite ends thereof for lrolling engagement with the tracks. A second carriage H33 is supported by carri-age (S3 'for ln.rve'1nent thereon in transverse relation to the direction of movement of the carriage +00.

To this end the carriage 86 is provided with tracks tt-1l and 495, and the carriage 493 is provided with rollers o5 and ll .forrolling move ment on said tracks. The carriage (U3 supports e vertically disposed X-ra'f Atube i138 which projects X-r'ays 'downwardly Aas indicated et H18.

- The carriage iJ is provided with .an elongate plating 82 and a centre. ly locat o' tungsten butj ton 83.' The'twe catliocles are selectively oper-- able. Wlien the cathode T8 is operable, .2s-shown in Fig. 151A, :it projects@ directed beam of electrons onto the butto-n 213-. which radiates X-rays downwardly es in the conventional K-ray tube. Whentlie cathode "l2 is operable, as shown in Fig. 19B, it projects a lnroadbemn of electrons.

onto tn'e entire X-ray emitting surg'ace. Some ,of the X-rays are radiated 'downmireiy While others are transmitted through the lens 8| to a focal point or area. By shielding Vciti-ier of the X-ray sti-earns, the tube may be used either in normal fashioncr es an X-ra-y focusing device.

In 20A and .2GB Athere is shown a similar device 84 in which e. single not cathode assembly 85 .is used, instead o using two cold cathocies.

Otherwise. the device is-srbstantially t'n'e same in `for movement relative to the lens. A supporting' structure is i'nrovided comprising a. pair of xed oefening vl l to accommodate the Xf-ray tube-and to permit movement thereof during `neoveinentot the-carriage m3.

{B5/ineens of this arrangement, the X.-ray tube may be moved in scanning relation to the .lens 9S to effect successive transmission of certainof the X-rays to .the focal point or area 99. The scanning movement is indicated in Fig. 24 by the broken line represcntetion H I. As indicated by the arrow iead's, the scanning movement comprises successive 'transverse .motions back end forth in parallel paths corresponding to the rows of Xi'ay translnissive elements of the lens 28.

'he scanning is eected `by first moving the earriage W3 from one end of its limited path of travel to the other end thereof, then .moving the carriage lf o short distance, tiren moving the carriage 92 cock 'to the rst end of its .limited -path of travel, and so on until the-entire scanning operation is completed. The movemenisof .the

'carriages I nziy be effected manually or by suitable driving mechanism. As shown in Figs. .L-l and 22 the carriage S80-'muy be driven by meinsl of a scr iv shaft l i2 'rotate-bly supported by standards SBVand '89 and a screw-engaging nut member 'H3 ,provided on the carriage m0. The screw shaft H2 may be driven by motor drive unit l lll which may be caused to operate intermittently .to eiect the desired intermittent motion of carriage i130. The carriage -103 may lne simil-arly driven by means of a. screw 'shaft Yl l5 rotatably supported by carriage IDU, .and a screw-engaging nut portion ll provided on thecarriage |83. The `screw shaft H5 may be driven by .a motor drive unit Il? which may bec-used to operate intermittently so :is to 'effect the desired intermittent movement of the carriage $0.3. 'Suitable automatic controlling means maybe utilized to control tli'e operation ofjtlie driving units lli .and lll. However, these units could 'be manually controlled by me nelly operable' switches.

Considering further the results 'accomplished by tie scanning movement of the Xfr-ay tube-H33, it may be vassumed that the positionof the X-rey tube as shown in FigsJZl and .22 is the starting position. In this position of tlie tube one. of the Xrays from the tube Will pass through the trensmissive 4element of lens 98 at the corner l thereof, as may be seen from Figs. 21 and 23. Y'

the tube goes Vthrough its first transverse-SCHH? motion'. different X-raystherefrom `rill'lJaSS successively through the transmissive elements in the rirst row of such elements, as indicated in Fig. 24. This selective and successive transmis'- sin of .diferent X-rays to the focal point or area is continued during each transverse scanning motion ofthe X-'ray tube. The X-r'ays which are not transmitted are -absorbed by the solid portions of the lens and -by the shielding plate .95.

The above-described apparatus is' particularly useful in hospitals and 'other places for localized Xeray treatment of the human body. With this arrangement the X-ray lens-'98 Vstationary and therefore the focal point or area 99 is fixed. .lt is an'easy matter, therefore, to place a patient beneath the lens andthe shielding plate 95 in proper position so that the particular portion of the patients body to be treated coincides with the focal point or area 59. During the treatment, the portion of the body to be treated issubjected to the successively transmitt'edX-rays which vare permitted to. pass to the focal point or area. 89 by reason of the above-dc-scribed scanning movement of lthe X-ray time. Such treatment is particularly applicable where it is desired that a localized point or area or' the patients body shall receive mild X-ray treatment over a time interval, rather than a. strong Xray treatment during a very short period of time. It should be noted, also, that the treatment by means of this apparatus can he varied by, plugging some of the passages of the X-roy lens with material which is non-tra-nsrnissive to X-,raysso that only someof the passages'will be effective to transmit 'X-rays. It should, also, be noted that the apparatus may employ an ordinary X-ray tube and does not'require an-y special tube construction.

As indicated previously, the present invention is intended for application to any purpose for which it may be suited, and is not limited to X- ray treatment of the human body. By tvay of example, the invention may be applied to X-ray photography or Iiuoroscopy, and when thus applied it has important advantages as may he seen from a. consideration of Figs. 25 to 28. In Fig. 25 there is shown an X-ray emitter I I 3 radiating X-rays IIS divergently from a point I'Z. An image plate or screen is represented at I2 i This arrangement is that commonly used in X-ray photography cr iluoroscopy. In the case of a fiuoroscope, -for example, an object such as the cube I2'2, when placed between the X-ray source I ZD and the screen l2 I, `will produce'an image on the screen 1 2I as shown at I 23 in Fig. 26, the image being visible from a viewing position suchas represented at I 24 in Fig. 25. Now ifthe object is removed a-Way from the viewer to another position, as shown by the .broken line illustration' in Fig. 25, the Aimagewill be larger as may be seen from the projection lines. This is contrary `to reality, since anobject should appear smaller as it is moved away from the viewer point. Conversely, if .the Object E22 is moved toward the viewer the image will appear smaller. Furthermore, in any particular position ofthe object the image size is larger than the object itself, which is also contrary to reality. Thus the arrangement of Fig. 25 gives an incorrect reproduction of the object.

In Fig. 27 there is shown an arrangement utilizing the present invention, wherein the lensA I25 of 'this invention directs X-rays E28 convergently toward a 4focal point l2?. A fluores- 10' cent screen is represented at I28. An object I2! produces an image as shown at 130 in Fig. 28L the ima-ge bei-ng smaller 'than the object. Now if the Objectis moved aivay from the viewer to a. Aposition such as indica-td by the broken line illustration in Fig. 27, the image will appearsnzaller. Conversely, if the object is moved toward the viewer the image will appear larger. Th; is in accord with reality, and it will be seen that utilization of the present invention gives a true viewing of the ocject. By utilizing the invention in stereoscopc X-rey apparatus,- a true perspective of the object may be obtained. Thustwo lenses may be used to form two .images which may be viewed stereoscop-ically :or which may be photographed stereesc'opi-cally to obtain a truev perspective viewing of the object or t-o obtain a. true perspective picture of the object.

From the foregoing description it will be seen that the invention is capable of various applications and embodiments. It will be understood.

of course, that the embodiments illustrated and' described are-merelyl exainplary and are not in tended to limit the invention.

We claim:

1. A device for producing directionally concentrated Xerays, comprising means for emitting electrons.- an X-ray producing surface arranged to receive -electronsfro'm said rst means. a. lens member arrangedior subjection to X-rays from said surface, said member having rectilinear X-ray transmissive elements out being otherwise non-transmissive to X-rays, said transmissive elem-ents 'converging toward a focal point or area, whereby selected X-rays produced by said surface are transmitted by saidv elements Itoward a focal point or area, and means :for

'causing impingement of electrons only on the` portions of said surface adjacent to said elements'. v 2. A device according to claim 1, including means for producing an electron beam, means for causing said beam to 'scan the X-ray producing surface, and means Viorcontroliing the in;- tensitycf the beam according to the pattern of said lens member.

3. In combination, means forprodueing a nar.-

l'oiv electron beam, an electron-excitable -X-ray' producing surface arranged for impingement Lof said electron beam thereon,A means for electing scanning motion of said `Dea-m to cause the bea-in to sean said surface, and means arranged eo- Opcratively with said surface to effect selective transmission of '4C-rays from different points of 'said 'surface dion" Afredetermined paths, whereby the scanning motion of said beam causes suc- 'cessive ,transmission of Xrays from said points Aalong said paths.

4. In `com'cina-tion, means for producing a. narrow electron beam, en electron.e xcitable X-ray producing surface arranged for impingement of said electron beam thereon, means for ele'cting scanning motion 'of said beam to cause the beam @aiming motion QI said beam. to. cm- 15a the-bca siveY elements, extending from d-ernt pointsl of said surface but being otherwise. non'transmssivo to X-raysi said transmssive, element: coilverging toward a. focal arca, whereby the scimning motion of Said beam causes' successive transmission of X-rays from said points 'along said elements toward, said focal area.

6. In combination: means for ppoducng a narrowl electron beam. an electromexcitablc X-ray producing surface arranged 01' mpngement'o! said electron beam 'hercom means for :effecting scanning motion of 'said benin to cause the beam tAQ Scan said surface, means arranged cooperatively with saigd aurfa'ce to rgect selective transmission of X-rays--from rierentmints, Qi said surface along predetermined lfm,lu a, whcre,by the sca-lming motion of aid beam causes successivo transmission of ESL-rays from said pQlDs along said mths, and means, for preventing saidv beam from impin-gn on said surface. at points other than the aforementioned punit-3.

7. In combination; en X-ray-produomg mbe including mea ns forproducinga lfxarroiav eocron bel'un, an electron-excitable Xqa'yf producing Sur-4 face on 'which said beam impmges, means for effecting scanning motion of ,said beam to cause the vbeam to scan said surfaco, and means for controlling the intensity of saidc beam; an X-rw. directing mem'er .adjacent s s-d surface hav-ing X-ljay transmsjsive :elements ext'cndng from dif` ferent points of 4.Sad surface but being' otherwise nmbtra-ngmssve to X-rays; a. sg'n-pro:ucil1g cathode ray .tube yhaving s target surface with a pattern weon corresponding to the entrance' facefof X-ray directing member; means for cfectng synchi-Qnou cenn-A nng of both of said tubes; and means for apply`- the signal produced by thev lash-Iectcd, tube to. the, bea-m ntnsity-contflfoil-ng means' of the mamy,

ning means and a face on which said beam mpngcs. means for eefxtng. s oclming rnoionvo :md beam to cause l the beam' to scan .s surface, und means for controlLng the mcnmj o jme. 'im X-ray lens, memo?? {adir-cent auf@ ce having vXLHIS 'g from. diferent points o said surface but being otherwise no11- tram-missive to X-roys said transmss'we e1ements conf'crging toward l21.v o'cal area; a signalcathode ray tube. b fying mummia JQHN l; BAR'LQW. JACK A. .BARTOW v @BEY iD. n-'ngLAUGHLm n nefmnees cited in am@ me. of this patent 1mm-@n STAT-Es- @xmms 

